In the melt reduction of iron oxides, which may include other components as in the case of iron ore, the iron oxide material in powder or granular form is continuously fed to a molten carbonaceous iron bath where the carbon reacts with the oxygen to form the crude iron bath which is tapped continuously or as required from the hearth containing the bath.
When practicing this technique, it is often the second stage of a two-stage reduction of the iron oxides, the first stage comprising a prereduction effected by heating the iron oxide material while in a reducing gas, this first stage only partially reducing the iron oxide content of the material involved. In the case of iron ore, the gangue, of course, results in a slag floating on the molten bath, and the latter may also support a layer of carbonaceous material such as coke particles. Such layers floating on the bath prevent direct contact with the latter by the iron oxide material, preventing a rapid reduction of the iron oxide.
The above slow-reaction disadvantage can be corrected if the bath is heated to keep it molten via properly designed induction heating arrangements, but induction heating is relatively expensive as compared to arc heating.
It is desirable to feed both the iron oxide material and the carbonaceous material, and possibly flux, to the bath in the form of streams of powder having a relatively fine particle size. Particularly when arc heating is used, this practice involves the disadvantage that the powder material is blown about above the carbonaceous bath, making difficult its feeding to any desired location.
Also, for the melt reduction technique the hearth containing the carbonaceous bath is ordinarily enclosed so that the gas resulting from the reaction of the iron oxide with the carbon can be carried away via an exhaust arrangement. Therefore, if the powdered material is floating around within the enclosed hearth, an undesirably large amount may be drawn off by the exhaust instead of contacting the bath.